The invention relates to a shaft frame, particularly for power looms.
The shaft (also called a heddle shaft) of a power loom is formed by a shaft frame, on which heddles are retained. Each of the heddles has an eyelet for a warp yarn passing through it. A motion of the shaft in the longitudinal direction of the heddles therefore shifts the warp yarns out of the plane of the warp yarn, forming a shed, for instance for inserting a weft yarn.
In modern power looms, the heddle shafts are moved back and forth at high speed. The accelerations and braking forces are so great that the heddles, which as a rule are held with some play on the shaft frame, hit their bearings and dig in there. This process generates noise and wear and puts limits on the operating speed of a power loom.
The attempt has therefore already been made to reduce the play of the heddles on the shaft frame. To that end, German Utility Model G 94 13 705 proposes providing a narrowly dimensioned transverse groove on the heddle head of each heddle, and a jiblike protrusion of a driving support rail, which is part of the shaft frame, belongs in this groove. However, the prerequisite for this is suitable adaptation of the heddle heads. Moreover, forces introduced into the heddle head relatively at only individual points.
From German Patent Disclosure DE 199 62 977 A1, it is known to dispose a strip of a material with damping properties on a flank, facing toward the heddle heads, of a shaft frame in order to embody a yielding stop. This stop is subject to wear when the heddle heads periodically strike it.
From European Patent Disclosure EP 0 874 930 B1, it is known to secure heddles to the heddle frame without play. To that end, a heddle support rail that reaches through the heddle heads has an expandable element, which is formed for instance by a hose that can be subjected to a fluid. In the non-expanded state, the heddle heads can be slipped onto the heddle support rail. If the element is expanded by subjection to fluid, then the heddle head is firmly clamped to the heddle support rail. It is thus seated without play.
This embodiment is relatively complicated and expensive.
With the above as the point of departure, it is the object of the invention to create a heddle shaft which, at little effort and expense and with high reliability makes an increased operating speed of power looms possible.